Networked RAID Arrays · Fibre Channel, SAS, iSCSI and Multiprotocol Fibre Channel/iSCSI networked RAID Arrays. Introducing a new category of networked RAID storage solutions . The

Dot Hill AssuredSAN™ Series

Fibre Channel, SAS, iSCSI & Multiprotocol Fibre Channel/iSCSI

Networked RAID Arrays

AssuredSAN™ 2002 Series

AssuredSAN™ 3000 Series

Dot Hill AssuredSAN™ Series.The most versatile and trusted networked RAID portfolio in the storage industry.

Data is the lifeblood of the industrial world. System failures can be rectified regardless of the cause but the integrity of data is vital for business continuity, quality of service and in many cases it is a legal necessity. So why would anybody trust their most valuable asset to a storage system that was just ‘good enough’?

Dot Hill have been delivering innovative storage solutions for well over two decades, although for much of that time the Dot Hill brand underpinned the storage portfolio of many of today’s leading A-brand technology vendors.

It is no surprise then, that our networked RAID technology is probably the most robust in the industry today, having been validated by the most demanding OEM customers and deployed in over 350,000 installations worldwide; supporting the lifeblood of every conceivable industry sector.

We take pride in being one of very few storage vendors who own the intellectual property that is at the core of their RAID engine. Not only does this ensure that we control the utmost quality that has become expected by our customers, but we can be consistently first to market with innovative, efficient and cost saving data storage solutions.

With the introduction of the Dot Hill AssuredSAN Series you no longer have to choose a storage solution that is just good enough!

Dot Hill AssuredSAN™ SeriesFibre Channel, SAS, iSCSI and Multiprotocol Fibre Channel/iSCSI networked RAID Arrays

Introducing a new category of networked RAID storage solutions

The Dot Hill AssuredSAN Series introduces a new category of feature-rich, entry level storage solutions that rival more costly midrange products, providing IT managers with access to cost effective and energy efficient storage solutions that may previously have been beyond budget.

Both the AssuredSAN 2002 and 3000 Series offer a choice of Fibre Channel, Serial Attached SCSI (SAS) or iSCSI host interface, the option to expand seamlessly with JBOD expansion chassis, the flexibility of SAS, SATA and SSD technology with both space saving 2.5-inch or standard 3.5-inch drives.

What really sets the AssuredSAN Series apart from the competition are the innovative and unique technologies designed to safeguard vital business data, reduce total cost of ownership, protect the environment and improve storage performance.

Dot Hill Storage Technology - the standard for others to follow

EcoStor™ - the first ever implementation of battery-less cache protection using super capacitor and flash memory to provide perma-nent power loss data protection

Simulcache™ - is our unique low latency cache mirroring design that maintains fantastic write performance in a dual-controller RAID configuration

AssuredSnap™ - provides volume snapshot capability, allowing point-in-time copies that can be used to maximize business continuity

AssuredCopy™ - creates a full volume copy providing further safeguards against vdisk failure & eliminating application I/O conten-tion when accessing the same data blocks

AssuredRemote™ - remote asynchronous snapshot replication offers a very affordable low maintenance approach to remote office data protection and disaster recovery

Data-in-place migration - through a highly modular design we provide maximum forward/backward compatibility, ensuring in-vestment protection and avoiding that forklift upgrade


2002 Series: 4Gb Fibre Channel, 3Gb SAS or 1Gb iSCSI host interface

3000 Series: 8Gb Fibre Channel, 6Gb SAS or 1Gb iSCSI host interface

Optional hybrid controllers offering 8Gb FC and 1Gb iSCSI in a single system

AssuredRemote™ built-in array based Remote Asynchronous Replication

Fully backward compatible with 200x Series 4Gb FC

Drive spin down for up to 20% power saving

Super efficient 80 PLUS-rated power supplies

Common Features:

AssuredSnap™ built-in array based snapshots

AssuredCopy™ built-in volume copy capability

EcoStor™ battery-free cache protection

Simulcache™ low latency RAID cache mirroring

Mixed SAS, SATA and SSD drive support

12 3.5” drives or 24 2.5” drives per chassis

Common 2U form factor across entire range

Key Features

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AssuredSAN 2002 SeriesDot Hill’s AssuredSAN 2002 solu-tions combine high performance and high capacity storage with the ease of our web based RAIDar manage-ment GUI which provides a complete set of features and tools to ensure that storage administration is the easiest job in the data centre. A choice of 4Gb FC, 3Gb SAS or 1Gb iSCSI host connectivity is offered with a range of drive types and formats to meet the needs of a vast spectrum of business applications.

AssuredSAN 3500 Family 6Gb SAS SystemsThe AssuredSAN™ 3520 and 3530 are next generation 6Gb SAS host interface systems offering excep-tional performance in direct attached environments. Delivering 6Gb over 4 lanes of SAS, for total throughput of 24Gb per SAS connection; even fast-er than certain fibre channel alterna-tives and much easier for the novice to install. 6Gb end-to-end delivers the best performance and leverages the latest disk drive technology, making them a good choice for applications such as video post-production, HPC blade server systems or environ-ments where high-speed and high-density, local storage is required.

AssuredSAN 3700 Family 8Gb Fibre Channel SystemsThe AssuredSAN™ 3720 and 3730 are next generation 8Gb fibre chan-nel systems that will improve read and write performance for any stor-

age area network, making them the first choice for applications such as databases, business analysis, and video streaming.

AssuredSAN 3900 Family 8Gb Fibre Channel & iSCSI Multiprotocol SystemsNew! The first Multiprotocol SAN RAID Systems delivering 8Gb Fibre Channel with 1Gb iSCSI in a 2U size! Featuring array-based remote rep-lication, plus Ethernet SAN/WAN connectivity these systems can be used to implement disaster recovery, meet compliance needs, or imple-ment a centralized backup solution.

AssuredSAN 3100 Family 6Gb JBOD Expansion ArraysQuickly and easily expand your 2002 or 3000 storage systems with JBOD expansion arrays offering a choice of 2.5” or 3.5” drives connected with a true 6Gb SAS backplane that is fully backward compatible with our legacy 2000 Series.

Dot Hill AssuredSAN Data Management SoftwareWith Dot Hill’s full suite of Data Man-agement Software (DMS) solutions you have the assurance that you can store, instantly back up, and instantly restore, and you don’t have to be a storage expert to make it work. Our built-in AssuredSnap™, Assured-Copy™ and AssuredRemote™ data protection software provides simple but efficient tools to boost productiv-ity and support disaster recovery.


Maximum choice with high density 2.5” or standard 3.5” drivesFor many years the 3.5” drive has been the mainstay of both desktop computing and the enterprise data centre. With the need to produce more compact designs within the portable electronics industry the 2.5” drive form factor has seen significant development both in performance, capacity and power efficiency. The AssuredSAN 2002 and 3000 series offer RAID head units and JBOD expansion chassis that accommo-date 24 2.5” drives within the same 2U (rack unit) form factor as the standard 3.5” versions. Through our drive to maximize flexibility, 2.5” RAID head units can utilize both 12 bay 3.5” and/or 24 bay 2.5” JBOD expansion chassis up to the maximum drive capacity of the configuration. This enables storage solutions to be deployed that simultaneously cater for performance density and storage density applications.

First to market with super energy efficient 2TB 12 bay 2U RAID3.5” drive technology remains the first choice for high capacity applications where single SATA drives offer 2TB and will continue to increase, offering a great alternative to tape as secondary storage. The Dot Hill 2000 series arrays were the first to leverage Western Digital’s enterprise-class WD RE4-GP 2TB hard drives with WD GreenPower Technology™, the world’s highest capacity drives which also offer energy efficiency. This industry first resulted in 24TB of RAID protected storage in a compact 2U (rack unit) form factor delivering up to 60% power saving over traditional 1TB drive technologies.

TECHNOLOGY SPOTLIGHT: 2.5-inch Drive Technology

Development in 2.5” drive technology has seen significant investment to supply high capacity, high performance drives with the lowest possible power consumption for the laptop computing and games console sectors. As the performance and capacity of these smaller form factor drives approach that of their 3.5” cousins it is no surprise that their suitability for the enterprise data centre has been under the spotlight in recent years. Floor space, power provisioning and cooling are key data centre challenges which the 2.5” drive can address head on, therefore many analysts and manufacturers predict that the 2.5” drive is destined to be the new king of the data centre for high performance applications. The 2.5” drive when compared side by side to the nearest 3.5” equivalent it will certainly shine in terms of power requirements, perhaps 50% or more below that of a typical 3.5” drive, however total capacity and performance still lags behind by as much as 25%, although improvements are rapidly closing that gap.

The lower performance of 2.5” drives can be managed through increasing the drive count, for example, two 2.5” SAS drives in a RAID configuration will most definitely outperform one fast 3.5” SAS drive in every workload. The power required for the two smaller drives will not be higher and the total capacities may be similar. This performance density and power efficiency equation can be taken further, you can easily imagine that a simple RAID with four 3.5” drives could be replaced by six to ten 2.5” drives. These would not consume more power than the 3.5” drives, but resulting performance would be 50% to 2.5x higher, depending on the configuration.

AssuredSAN 2002 Series - Simplicity, flexibility and reliabilityThe AssuredSAN 2002 family offers simplicity through the intuitive RAIDar web based management inter-face which is common across the entire range regardless of which host interface or drive type is chosen. With a wide range of drive types including SAS, SATA plus two levels of Solid Sate Drive (SSD) to choose from, combined with the option of either 12 3.5-inch drives in a 2U chassis or 24 2.5-inch drives in a 2U chassis it is clear to see how the AssuredSAN series is one of the most flexible storage solutions on the market today. All systems employ redundant field replaceable components including drives, fans, power supplies and RAID controllers to ensure maximum availability of business critical data.

The 2002 series also offers bundled appliance solutions that arrive fully licensed with AssuredSnap™ and AssuredCopy™ data protection software.

AssuredSAN 2002 and 3000 Series Part Numbering made easy

Dot Hill AssuredSAN™ 2002 Series4Gb Fibre Channel, 3Gb SAS and 1Gb iSCSI networked RAID Arrays

TECHNOLOGY SPOTLIGHT: SimulCache™ - Low Latency Cache Mirroring

Application environments such as data acquisition, large scale CCTV or video post-production present a very different data workload to general IT based systems. A huge amount of data is transmitted continuously from the source to the application; in contrast, most IT applications generate lower and more sporadic workloads. The processing overhead for writing high throughput sequential data streams to disk is therefore an important factor in overall system performance.

This is especially important in dual controller RAID configurations where the incoming data must be written to two controllers. Dot Hill’s networked storage arrays employ SimulCache: a unique patented data caching architecture providing exceptionally high bandwidth write performance in RAID protected configurations. SimulCache uses an extremely low latency internal bus to copy incoming data from the active to the standby controller without the noticeable drop in write performance experienced with traditional RAID cache designs.

3 - iSCSI Host Interface5 - SAS Host Interface7 - Fibre Channel (FC) Host Interface9 - Hybrid FC + iSCSI Host Interface*

2 - 2.5” drives (max 24 per chassis)3 - 3.5” drives (max 12 per chassis)

2 x x 2

3 x x 0

* 3000 Series only

Dot Hill AssuredSAN™ 3000 Series8Gb Fibre Channel and Multiprotocol 8Gb Fibre Channel with 1Gb iSCSI Arrays

Complete Flexibility & Investment ProtectionThe Dot Hill 3000 Series offers investment protection and non-disruptive storage upgrades through the use of 8Gb Fibre Channel (FC), or dual interface 8Gb Fibre Channel with 1Gb iSCSI solutions that are fully backward-compatible with existing 4Gb Fibre Channel and iSCSI installations. With the addition of drive spin-down, mixed drive type support and dual protocol interfaces, users can now combine both high perfor-mance primary volumes and secondary storage with different usage profiles in the same physical unit.

Simple and Affordable Remote Replication with ‘Set & Forget’ SimplicityAssuredRemote™ is a key component of the Dot Hill 3000 Series Architecture, enabling IT professionals to solve many of today’s data protection challenges by building complete solutions for business continu-ance, disaster recovery and regulatory compliance.

Replication is simply the ability to capture a moment in time of a disk volume and replicate it to a different location. It allows the remote copy of data not only to function as a backup, but also provides the ability to restore to a specific point-in-time so that systems can be recovered to a moment before a significant event, such as data corruption, application failure or a site disaster.

The impact of service downtime can be very serious and replication forms a back bone to ensure business continuity. Replication can be scheduled to keep business impacts low and can be used to restore your business operations within minutes.

iSCSI & 8Gb FC in a single systemThe AssuredSAN™ 3920R and 3930R deliver both 8Gb FC and 1Gb iSCSI in a single hybrid array deliver-ing maximum flexibility. These systems enable users to leverage both iSCSI and Fibre Channel storage to perform file and block level storage and replication both locally and across a wide area network (WAN) from a single unified storage system.

TECHNOLOGY SPOTLIGHT: EcoStor™ - true Green cache power fail protection

Traditional RAID storage array designs use internal batteries to provide charge to hold the contents of the RAID cache in the event of a power failure. A fully charged cache battery can be expected to hold this data in memory for perhaps 72 hours. If power is not restored within this time, cache data that was waiting to be flushed to disk will be irretrievably lost. This is a best case however, batteries have a finite life and their performance deteriorates over time giving unpredictable cache support. Another major problem with cache batteries is the time taken to fully recharge after a power failure, during the recharge time which can be in the order of hours the cache data is no longer fully protected; a big issue in the event of intermittent power failures. Dot Hill AssuredSAN Series arrays eliminate cache batteries completely using our patented EcoStor™ technology which copies cache data into a permanent flash card so that data is never lost no matter how long the power outage. It also provides almost immediate cache data protection when the supply power is restored.

The typical life of a RAID cache battery in a conventional disk array is two years, after that time it will need to be replaced resulting in service costs plus battery disposal which will add to the ever increasing landfill sites. EcoStor™ with super capacitor technology has a typical useful life of 10 years. In addition the whole storage array including the material used in super capacitor technology is fully compliant with global waste disposal directives such as RoHS and WEEE providing truly environmentally friendly data protection.

Dot Hill AssuredSAN™ 3000 Series8Gb Fibre Channel and Multiprotocol 8Gb Fibre Channel with 1Gb iSCSI Arrays

Flexible Prepackaged Storage Solutions with Data Management

The Dot Hill AssuredSAN 3000 channel product line offers customers a range of prepackaged, Dot Hill branded storage solutions, that are fully integrated with our core data management software suite (DMS). The solutions are easy to install and manage through an intuitive web based graphical user interface (GUI) which is common across all of our storage platforms. The product line is available with three levels of integration offering both standalone hardware RAID platforms, plus two levels of DMS licence integration to include our AssuredSnap, AssuredCopy & AssuredRemote data protection technologies.

Drive choices for every application - SAS, SATA and SSD

Each business application will have a data workload characteristic that will suit a particular drive technology. For online transactional processing applications (OLTP) it will be high performance SAS that will deliver the throughput needed to handle these random read/write data workloads. For applications with more sequential write characteristics such as video surveillance (CCTV) or video post-production, high capacity SATA drives may offer the most cost efficient solution. Due to their high storage density SATA drives also offer a very cost effective alternative backup medium to tape. Using SATA as secondary backup will deliver massive recovery time advantages and with their hot-swap capability can easily be taken off site as part of a secure disaster recovery policy.

The solid-sate drive (SSD) is a relative newcomer to the enterprise data centre. Previously a niche solution for embedded high performance applications, the recent cost reduction and capacity increase of SSD technology has established its place as a feasible new ‘tier zero’ drive solution for applications that require the ultimate in performance or power efficiency. Dot Hill AssuredSAN 2002 and 3000 solutions offer various SSD drive options that can be mixed with both SAS and SATA technologies to create a true tiered storage architecture within one easy to manage configuration.

TECHNOLOGY SPOTLIGHT: Solid State Drive Technology (SSD)

Mainstream SSD deployment currently resides in the ‘early adopter’ stage of its technology adoption lifecycle, and like many technologies that are gaining momentum there are trade-offs that need to be considered at this initial stage.

Firstly, the cost per gigabyte for SSD will be higher, and in some cases significantly higher, than mechanical drive equivalents, so if improved I/O performance is the driving factor the cost per/IOP will be a useful calculation to make.

Secondly there are two main configurations used in SSD manufacture: Single-Level Cell flash memory (SLC) found in the most expensive and performant drives, which as the name suggests uses a single NAND flash cell to store each bit of data. The alternative, Multi-Level Cell flash memory stores 2 or more bits per cell and is found on more cost effective and usually higher capacity SSD devices.

When considering which SSD technology is right for an application a useful analogy would be to think of SLC as the high performance and super reliable SAS drive of the solid-state world, while MLC fills the place of the less resilient but higher capacity SATA drive.


Fibre Channel - The cornerstone of Enterprise Networked StorageThe continuation of FC networked solutions as the keystone of our shipments in 2010 serves as testa-ment to its position as the storage area network (SAN) solution for enterprise computing, and the integrity of our 7th generation FC RAID solution stack underpinned by our own intellectual property. Fibre Channel technology has been advancing at a pace in keeping with Moore’s Law and infrastructure vendors have been rapid to offer 8Gb solutions this year with price parity to the previous 4Gb standard. Industry ana-lysts, customers and manufacturers agree that by the end of 2010, 8Gb FC technology will be widely adopted by organizations around the globe.

With over 90% of today’s SAN applications and devices ticking over nicely on 4Gb FC you may wonder why the market needs another speed bump right now. Although 4Gb SAN infrastructures have generally provided sufficient bandwidth for today’s SANs, the digital information and server virtualization explosion continues to drive the need for a higher-performance infrastructure. In addition, the exponential growth in the amount of data being created and the increased amount of data that must be managed and stored in order to comply with regulatory and financial requirements is driving the demand for higher speed network-ing. Aside from the organic infrastructure growth required to keep pace with technology advancements, there are a group of increasingly data-intensive applications that can take instant advantage of 8Gb FC to improve productivity, reduce time to market and bring a welcome boost to business continuity:

8Gb Fibre Channel - Urgently needed throughput for Server VirtualizationYou may argue that application servers which require and drive FC bandwidth to the limits are in the minority. However, the fact that the average application server is under utilizing its hardware provides a key application area which can benefit immediately from 8Gb FC. Virtualization servers combine multiple application servers into one box in order to maximize utilization of the server hardware. This means that current FC speeds that would be more than adequate for a single application server can suddenly become inadequate for the virtualized group. So where a single e-mail or database server might not need 4Gb per second throughput, a group of virtualized e-mail and database servers certainly could saturate the available bandwidth and immediately take advantage of 8Gb FC.

Maximizing performance for Storage VirtualizationStorage Virtualization servers are another group of servers that can take immediate advantage of 8Gb FC. These servers consolidate the functions of multiple storage arrays by abstracting logical storage from the underlying physical storage. Even if there are legacy storage arrays within a SAN infrastructure that still employ 2/4Gb FC, the storage virtualization server can use 8Gb ports to aggregate access to all arrays within the SAN infrastructure. Also, since the 8Gb FC ports are compatible with existing 4Gb and 2Gb FC, storage virtualization servers can be used by the application layer at 8Gb while still being used by individual application servers at 2/4Gb, or even at 1Gb using iSCSI without change.

Model Host Ports Chassis Max. CapacityDrives per tray | system

Drive Support Drive Size*

Dot Hill 2722 4 x 4Gb FC 2U24 24 | 96 SAS,SSD 2.5”

Dot Hill 2732 4 x 4Gb FC 2U12 12 | 96 SAS,SATA,SSD 3.5”



Dot Hill 3930 4 x 8Gb FC & 4 x 1Gb iSCSI 2U12 12 | 96 SAS,SATA,SSD 3.5”

Dot Hill 3920 4 x 8Gb FC & 4 x 1Gb iSCSI 2U24 24 | 96 SAS,SSD 2.5”

Fibre Channel (FC) Storage Solutions

Dot Hill AssuredSAN Fibre Channel Arrays(4Gb, 8Gb FC and Multi-protocol 8Gb FC with 1Gb iSCSI Arrays)


Serial Attached SCSI - The new standard for direct attached storageSerial-attached SCSI (SAS) is the extremely flexible successor to parallel SCSI and overcomes the perform-ance and scalability limitations of its long serving predecessor. SAS remains compatible with the SCSI com-mand set providing a clear migration path for existing SCSI users. The true potential of SAS resides in its flexibility; although not as robust as Fibre Channel (FC), the SAS protocol offers levels of performance and reliability that meet the demands of most enterprise users. The key differentiator over FC is the ability of SAS based systems to mix SAS drives with lower cost Serial-ATA (SATA) drives within a single storage sub-system. The prospect of Information Lifecycle Management (ILM) within a single drive enclosure becomes a reality, something not possible with mixed FC/SATA solutions on the market today.

Dot Hill take first place with SAS/SATA intermixMost major storage vendors released mixed SAS/SATA storage solutions during 2007 but very few were able to offer complete drive intermix within a single array enclosure. The Dot Hill 2000 Series was the first RAID family to reach the market offering unrestricted chassis level drive intermix. Many vendors were guarded over their early struggles to mix the technologies although it is known that for some the mechani-cal vibrations from 15k rpm SAS drives caused problems when placed alongside 7.2k rpm SATA drives that have a far lower vibration tolerance. In the race to release SAS/SATA storage arrays many vendors housed their SAS and SATA drives in separate enclosures or placed restrictions on drive placement within a single enclosure. The Dot Hill 2730 array enabled an A-brand storage vendor to achieve an industry first with full SAS/SATA intermix capability within their RAID portfolio.

SAS versus SATA positioning in the data centre

The SAS interface and drive mechanical construction provides levels of performance and reliability comparable to that of FC, however SAS is not a fabric technology and is intended to complement rather than replace FC in the data centre. Conversely SATA has origins in desktop computing and maintains a price point and reliably level to compete in that highly competitive market. Both SAS and FC drives are designed for continuous 24x7 operations whereas SATA drives are designed around a less arduous 8x5 duty cycle hence their mechanical construction uses fewer stabilizing parts to maintain a lower price point. The more economic construction of SATA also accounts for slower rotational speeds which typically lag SAS by 50%, although SATA capacity currently runs at double that of SAS with the 2TB SATA drive making its debut in the first half of 2009. It is also important to consider that MTBF figures for SAS and SATA drives are usually quoted with reference to their respective duty cycles making a like for like comparison a speculative calculation. Despite the lower performance and less robust construction SATA certainly has its place in the data centre assuming the limitations are well understood.



Dot Hill 2522 4 x 3Gb SAS 2U24 24 | 96 SAS,SSD 2.5”

Dot Hill 2532 4 x 3Gb SAS 2U12 12 | 96 SAS,SATA,SSD 3.5”



Serial Attached SCSI (SAS) Storage Solutions

Dot Hill AssuredSAN Serial Attached SCSI (SAS) Arrays(3Gb and 6Gb SAS Arrays)


iSCSI - An IP based SAN solution based on familiar Ethernet networkingInternet Attached SCSI provides a method of transporting SCSI commands over Ethernet using TCP/IP. It is important to differentiate this from Fibre Channel over Ethernet (FCoE) which is an emerging technology that carries the Fibre Channel protocol over Ethernet natively without using the TCP/IP transport layer. So with iSCSI you get an IP based SAN, while FCoE provides a FC based SAN carried over Ethernet. The po-sitioning of these two SAN solutions can be confusing to the end user, especially when iSCSI is incorrectly positioned as a FC SAN extension solution.

iSCSI provides block level storage over Ethernet using a unique protocol to carry SCSI commands, and a relatively inexpensive TCP/IP transport. This requires an iSCSI infrastructure to be managed differently, using different tools than the existing FC SAN management tools enterprise data centres use today. FCoE in contrast consolidates fabrics, while providing investment protection for existing FC SAN hardware and management tools, but also simplifies the overall data centre infrastructure in the same way as iSCSI by standardizing on Ethernet as a single physical transport.

Where does iSCSI fit in the SAN marketplace?Clearly iSCSI should not be positioned as a FC SAN extension solution as its true role is complementary to FC serving different market needs. iSCSI addresses standard applications outside the data centre provid-ing SAN technology for those who do not have a significant Fibre Channel infrastructure investment or the skills in-house to deploy such. Performance is also a key consideration with the majority of current iSCSI solutions residing on 1Gb Ethernet transport while the market waits for 10Gb Ethernet to mature.

Dot Hill iSCSI presents a familiar face

Our modular architecture is at the heart of every Dot Hill networked RAID solution. All of our RAID product families, regardless of host interface, are based on the same physical footprints using a single management interface and common field replaceable components wherever possible. This not only simplifies service, support and inventory management for our customers, but also reduces training costs as the management interface presented by our iSCSI solution will be identical to the GUI present on our SAS and FC host based equivalents. Furthermore, our modular architecture provides the utmost in investment protection allowing customers to upgrade their core infrastructure to take advantage of advances in RAID controller performance, or to take advantage of protocol advances while maintaining access and use of any JBOD expansion chassis containing crucial business data. We call this ‘Data-In-Place Migration’, a feature our competitors find very hard to emulate.



Dot Hill 2322 4 x 1Gb iSCSI 2U24 24 | 96 SAS,SSD 2.5”

Dot Hill 2332 4 x 1Gb iSCSI 2U12 12 | 96 SAS,SATA,SSD 3.5”



Internet Attached SCSI (iSCSI) Storage Solutions

Dot Hill Internet Attached SCSI (iSCSI) Arrays(1Gb iSCSI and Multi-protocol 8Gb FC with 1Gb iSCSI Arrays)

Dot Hill AssuredSAN™ Series.Choosing the right data protection technologies is vital to ensure business continuity.

With so many data protection and disaster recovery technologies available it can seem like a jigsaw puzzle for the end user when selecting the right pieces to ensure protection for vital business applications.

For the vast majority of corporations, business process downtime will equate to lost revenue and lasting customer dissatisfaction which could result in bankruptcy in the extreme.

Dot Hill understands the key considerations that need to be made when designing for business continuity. Our core data protection technologies provide the foundation for development and implementation of a complete disaster recovery solution.


Dot Hill AssuredSAN DMS - AssuredSnap™, AssuredCopy™ & AssuredRemote™With Dot Hill’s Data Management Software (DMS) solutions you have the assurance that you can store, instantly back up, and instantly restore, and you don’t have to be a storage expert to make it work through our AssuredSnap™, AssuredCopy™ and AssuredRemote™ data protection software. Each system comes with up to 256 snapshots to provide necessary protection for your business critical applications and this capability can be quickly and easily expanded through simple licensing as business needs demand.

The 2002 series offers bundled appliance solutions that arrive fully licensed with AssuredSnap™ and AssuredCopy™ data protection software. These appliance configurations are denoted the AssurdeSAN 2002-SA and 2002-ST configurations. AssuredSnap and AssuredCopy can be licensed and enabled of any 2002 or 3000 series array, except AssuredRemote which is only available on the 3000 series.

The 3000 series also offer pre-licensed configurations which are denoted the C, S and R series which are delivered with specific DMS features enabled at a discounted cost. Full DMS features can similarly be licensed for any variant in the AssuredSAN 3000 series.

Data Management Software (DMS)

Dot Hill AssuredSAN Data Management Software

Pre-configured DMS solutions for the AssuredSAN 3000 series

AssuredSAN 3000 C Series: Comprises of our standard channel products supplied without data management software integration.

AssuredSAN 3000 S Series: Comprises of our standard channel products supplied with discounted AssuredSnap and AssuredCopy software licences.

AssuredSAN 3000 R Series: Comprises of our standard channel products supplied with full discounted DMS licencing including AssuredSnap, AssuredCopy and AssuredRemote replication.

AssuredSnap™ - provides volume snapshot capability, allowing point-in-time copies that can be used to maximize business continuity

AssuredCopy™ - creates a full volume copy providing further safeguards against vdisk failure & eliminating application I/O conten-tion when accessing the same data blocks

AssuredRemote™ - remote asynchronous snapshot replication offers a very affordable low maintenance approach to remote office data protection and disaster recovery


Establishing Recovery Times & Recovery Point Objectives The successful implementation of any disaster recovery plan will hinge around two key metrics which have gained the popular labels of Recovery Time Objective (RTO) and Recovery Point Objective (RPO). Both met-rics need to be determined for each business application, and this calculation will map the IT infrastructure required to provide disaster recovery.

How much business process outage can we tolerate?The RTO is simply the amount of time an organisation can afford to operate without a particular business application being available. In other words, the RTO is the maximum allowable outage that the business can withstand before operation or service levels become unacceptable.

How much data can we afford to lose?The RPO deals with the amount of data loss an organization can withstand. For example, if a department store takes a daily backup every night at 10pm, but the following day a major outage occurs at 2pm, then any changes since the previous day would be lost. The RPO is this example is the previous nights backup. Of course for many organizations the recovery point granularity will be much more crucial, typically down to the last complete business transaction.

How does this affect our choice of technologies?When implementing a disaster recovery plan both the RTO and RPO requirements must be carefully analysed as a tightening of either parameter will usually require an increased investment in infrastructure, and/or the implementation of additional data protection technologies. A very useful way to interpret the myriad of data protection solutions is to understand how each contributes to the achievement of RTO and RPO. We will now attempt to categorize the most popular data protection technologies in this context.

Which technologies improve RTO & RPO?While many data protection technologies strive to maintain data integrity, subsequently improving RPO, others improve the overall storage system performance helping to deliver a tighter RTO through faster data restore times. Many data protection technologies will major in one particular recovery objective but there are certainly many that offer benefits in both recovery time and data loss protection. Table 1. outlines a selection of current data protection technologies and their core focus areas of support for disaster recovery.

Table 1. Data Protection technologies mapped against RTO/RPO improvement

RTO Improvement RPO ImprovementRAID 0 •RAID 1 •RAID 5 •RAID 6 •RAID 10 • •RAID 50 • •Clustering • •AssuredSnap •AssuredRemote • •AssuredCopy • •

Determining the parameters for an acceptable disaster


Out-of-the-box Data Protection for all eventualitiesA good disaster recovery plan must ensure that appropriate data protection technologies are available to cater for the wide range of eventualities that can manifest as a business continuity disaster. The most common events behind application downtime are hardware malfunction and human error, however other causes such as software malfunction, computer viruses and physical site disasters also play their part as illustrated in Figure 1.

Figure 1. Typical causes of business process downtime (Source: Ontrack 2008)

Recovery from a Computer VirusNew computer viruses are released every day. Antivirus software vendors update virus definition files in a constant race to detect and provide counter measures. Every so often a virus will strike before definition files have been updated; in these instances snapshot technology can offer a recovery solution. For example, if an e-mail system is compromised, snapshots can take the system back to a point before the attack, antivirus definitions can then be updated, and the system brought back to the point of attack by replaying the message log files. The message containing the virus should now be detected and neutralized using the new antivirus definition files during the replay.

Recovery from Human ErrorHuman error will often result in data being accidentally erased or stored to an incorrect location. In these instances snapshot technology can again be used to roll-back to a point in time before the mistake was made.

Recovery from a Software Program MalfunctionA software program malfunction may or may not result in data corruption. Snapshots may help restore data integrity if required, however a replication solution can provide fail over to a separate hardware and software platform which can eliminate or significantly reduce any downtime.

Recovery from a Physical Site DisasterThe affects of a physical site disaster can be guarded by a remote data replication solution with automated fail over.

Recovery from a Hardware or System MalfunctionRAID offers protection against disk drive failure and can be assisted by features such as media scanning which can be enabled to constantly monitor drives for bad blocks.

Dot Hill DMS - Built-in data protection technologies

Human Error

Software Program Malfunction

Computer Virus

Site Disaster

Hardware or System Malfunction

32%

44%

3%

7% 14%

RAID 0,1,3,5,6,10,50

Snapshot / Volume Copy

Replication

Human Error

Software Program Malfunction

Computer Virus

Site Disaster

Hardware or System Malfunction

32%

44%

3%

7% 14%

RAID 0,1,3,5,6,10,50

Snapshot / Volume Copy

Replication

Recovery from each of these root causes of downtime will benefit from different cat-egories of data protection technology; the choice being largely dictated by the degree of data loss or corruption caused by the malfunction. The Dot Hill range of storage solutions provides cover for all eventuali-ties with data protection technologies that include RAID, Snapshot, Volume Copy and Local/Remote Data Replication.


Can you afford application downtime for backup?So far we have considered how data protection technologies can reduce system recovery times (RTO). We must also consider the downtime required in order to successfully perform a backup of business critical data. For active transaction based applications it is usually necessary to complete any in-progress transac-tions and then temporarily freeze further activity during the backup of databases and their associated sup-port files. The term ‘quiesce’ is used when files are temporarily frozen in this manner. For many business services, application downtime during backup can be costly both in customer satisfaction and lost revenue.

How can AssuredSnap™ reduce application downtime?Dot Hill’s AssuredSnap is a data management solution for reducing backup windows and improving applica-tion availability. Traditionally, backup strategies have centred around nightly incremental or differential back-ups with full volume backups on weekends written to tape. With new disk technologies, disk-to-disk backup has gained wide-spread acceptance. While disk-to-disk backup is faster and more reliable than disk-to-tape, both require that applications and file systems be quiesced for the duration of the backup. Depending on database size, this can result in application unavailability measured in hours. For some operating environ-ments this may be unacceptable. AssuredSnap snapshots are logical point-in-time copies of volumes and can be created in seconds. With AssuredSnap, applications and file systems only need to be quiesced for an instant while the snapshot is taken. Once the snapshot completes, the application or file system is avail-able again for business access. The snapshot volume can then be mounted to the backup host, and the backup can commence without any further disruption to the business operation.

Traditional Backup Window Example: • Nightly incremental, differential or full backup is queued. • Target applications are quiesced stopping all transactions. • The backup job runs. • The applications are put back on-line.

Downtime will be a function of many components such as backup server speed, network bandwidth, disk or tape speed, and the efficiency of the backup application. Typically however, application outages will be in the order of 10s of minutes best case to hours worst case.

Using AssuredSnap™ to backup:AssuredSnap functions as follows:

• Disk subsystem cache is flushed for the target volumes • Host I/O to the target volumes are quiesced; the I/Os are queued in a buffer until the snapshots are complete. • Disk subsystem cache is re-flushed for the target volumes • Snapshots for the target volumes are taken in sequence • Queued IOs are released • The snapshot is then mounted to the backup server and the disk-to-disk or disk-to-tape backup completed, without further business process interruption.

Each snapshot takes less than a minute to complete. Therefore, application downtime is reduced to a minute or two depending on database and file sizes.

Reducing back windows with AssuredSnap™


Providing a foundation for Business Continuity?Like snapshots, volume copies can be used to protect against the accidental or malicious corruption of data. Entire volumes, folders or individual files can be quickly restored from the volume copy. AssuredCopy provides additional protection against complete volume or RAID group loss. Should a double disk fault occur in a RAID 5 set for example, the source data remains protected; this would not be the case with snapshots. Volume copies can be mounted to other application hosts in order to provide production data support for backup, rapid development and test, data mining, decision support and many other applica-tions. This can all be achieved without putting production data at risk or impacting application performance because access is to an independent data set.

AssuredCopy can have a significant impact on business continuity and productivity:

• Minimizes data loss • Rapid volume, folder or file restoration • Production copies for application support • Eliminates production application bottlenecks • Full volume backup windows reduce from hours to minutes

Further advantages of AssuredCopy include:

• Complete independent copy of a data volume or LUN • Source volumes may be master or snapshot volumes • Supports up to 255 copies per subsystem or up to 127 copies per controller • Read/write access to the source volume is possible during the entire copy process • The volume copy available to mount read-only or read-write upon copy completion • AssuredCopy can be scheduled or started manually

AssuredCopy operation and contrasts vs. snapshotVolume Copy is usually performed as a background operation, creating a complete physical and independent copy of a volume within a storage system. It is an exact copy of a volume as it existed at the time the action was initiated and consumes the same amount of space as the source volume, but is independent from an I/O perspective.

Volume independence is a key distinction of AssuredCopy (vs. snapshot which is dependent on the source volume until split off). Another distinction is that it takes a discrete action to create the copy of the volume, versus a continuous action as is typically the case for asynchronous and synchronous replication. A further distinction between AssuredCopy and AssuredRemote is that the volume copy must exist within the same physical storage subsystem.

Figure 2. AssuredCopy creates a complete independent volume copy

Protecting against data loss or corruption with

A

Volu

me

1

DCDC

BAB

Volu

me

1a


Protecting against disasters with Remote ReplicationTo ensure business continuity in the event of a local site disaster, data must be replicated to a remote site using a secure wide area network connection. Remote replication will ensure an identical copy of the live business application data is maintained at the remote site to allow business transactions to continue under any circumstances.

Demystifiying the various forms of Remote ReplicationRemote replication extends replication across the computer network to storage systems in separate physi-cal locations. There are several schemes which each have trade-offs in respect to performance, security and bandwidth efficiency. Implementations include Asynchronous Replication, Synchronous Replication and Snapshot-Based Replication.

Asynchronous Remote Replication

The asynchronous replication model considers that a local data write is complete when only local storage system has sent back an acknowledgment. The written data is then transmitted to the remote site, probably with a time lag, but the local application will not wait for any acknowledgement that the remote write has actually succeeded. Asynchronous replication has performance benefits for the local application but there is always a risk that the remote system may be missing the last update and data may be lost in the event of a failure.

Synchronous Remote Replication

Synchronous replication must be implemented to ensure zero data loss between local and remote sites. In this schema a data write operation is not complete until acknowledgment is received from both local and remote storage. Business application performance can decrease considerably with this method as most applications will wait for a write to complete before processing further transactions. A failure of the remote storage or just the network interconnection has the potential to freeze the local business application, which may then be forced to revert to unprotected operation.

Higher performance with Snapshot-Based Replication

Snapshot-based replication provides a very efficient form of asynchronous replication through the use of snapshot technology. Following an initial full data volume replication, Dot Hill AssuredRemote snapshot replication will periodically transmit just the data changes to the remote site. AssuredRemote provides a very cost effective and easy to administer remote replication capability for the small to medium enterprise. A disaster recovery solution based on AssureRemote can take full advantage of Dot Hill’s hybrid host interface storage arrays which offer both Fibre Channel (FC) and Ethernet (iSCSI) host ports on each RAID controller to make remote site replication very simple to implement.

Figure 3. AssuredRemote snapshot based asynchronous replication

Complete site disaster protection with AssuredRemote™

System 1 System 2

Read Request

Data TransferPrimary

VolumeRemote Volume




Dot Hill 2322 4 x 1Gb iSCSI 2U24 24 | 96 SAS,SSD 2.5”

Dot Hill 2332 4 x 1Gb iSCSI 2U12 12 | 96 SAS,SATA,SSD 3.5”





Dot Hill 2122 4 x 3Gb SAS 2U24 24 | n/a SAS 2.5”

Dot Hill 2130 4 x 3Gb SAS 2U12 12 | n/a SAS,SATA,SSD 3.5”




Dot Hill 3520 8 x 6Gb SAS 2U24 24 | 144 SAS,SSD





Dot Hill 3120 4 x 6Gb SAS 2U24 24 | n/a SAS, SSD 2.5”

Dot Hill 3130 4 x 6Gb SAS 2U12 12 | n/a SAS,SATA,SSD 3.5”

Dot Hill AssuredSAN 2002 Series - high performance systems for IO intensive applications4Gb Fibre Channel, 3Gb SAS and 1Gb iSCSI networked RAID Arrays

3Gb SAS JBOD Expansion Storage Arrays

8Gb Fibre Channel Arrays - Remote Replication Enabled(8Gb FC and Multi-protocol 8Gb FC with 1Gb iSCSI Arrays)

6Gb SAS JBOD Expansion Storage Arrays

Dot HillWorldwide Headquarters:

Dot Hill Systems Corp.1351 S Sunset StreetLongmont, CO 80501-6533Phone: 303-845-3200Fax: 303-845-3365Email: [email protected]

© 2010 Copyright Dot Hill Systems Corporation. All rights reserved. Dot Hill Systems Corp., Dot Hill, the Dot Hill logo, SANnet, Rapid Evolution Storage Architecture, and R/Evolution are trademarks of Dot Hill Systems Corp. Product names mentioned herein are trademarks and/or registered trademarks of their respective owners. Specifications and features may change without notice. 6-Aug-10.


Series Description Models Technology Interconnect Speed

Drive Size*

C Series Standard Channel Product:Dual ControllersAC PowerRack Attachment KitDot Hill Web BrowserUser GuideQuick Install Poster3 YR Warranty – Hardware“Try & Buy” DMS Software

3130C3120C3730C3720C3930C3920C

JBOD ExpansionJBOD ExpansionFibre ChannelFibre ChannelHybrid (FC & iSCSI)Hybrid (FC & iSCSI)

6Gb SAS6Gb SAS8Gb FC8Gb FC8Gb FC + 1Gb iSCSI8Gb FC + 1Gb iSCSI

3.5”2.5” 3.5”2.5”3.5”2.5”

S Series Standard Channel Product PLUS Core DMS Software License (AssuredSnap & AssuredCopy)

3730S3720S

Fibre ChannelFibre Channel

8Gb FC8Gb FC

2.5”

R Series Standard Channel Product with Core DMS Software License PLUS AssuredRemote™ Snapshot Replication

3930R3920R

Hybrid (FC & iSCSI)Hybrid (FC & iSCSI)

8Gb FC + 1Gb iSCSI8Gb FC + 1Gb iSCSI

3.5”2.5”

* In all cases SSD drives are small form factor 2.5” and housed in a carrier within 3.5” systems, check your local sales office for product availability

Dot Hill AssuredSAN 3000 C, S & R Series bundles with DMS licenses

UK Headquarters:

Dot Hill Systems Europe Ltd.Network House, Basing ViewBasingstoke, Hampshire, RG21 4HG+44 (0) 1256 840600Contact: David Thompson - Sales ManagerEmail: [email protected]: +44 (0) 7770852166

Documents

Networked RAID Arrays · Fibre Channel, SAS, iSCSI and Multiprotocol Fibre Channel/iSCSI networked RAID Arrays. Introducing a new category of networked RAID storage solutions . The